Issues table is a list of issues which appears after you run a query in the Navigation Area:
You can sort issues in the issues table by pressing the column name. Pressing the column name repeatedly toggles sorting.
You can customize the columns in an issue table by clicking ellipsis button in the upper right corner of the table and selecting which columns to show. Your changes to Issues table are applied immediately.
Columns with a number sign show the number of some entries (comments, work logs) attached to an issue. For example, Comments # column shows the number of comments – sorting by this column allows you to quickly see issues with most and least comments.